Illuminated license plates and illuminated display panels which may be attached to a motor vehicle in lieu of a license plate are well known in the art. Many of such prior devices involve illumination of the license plate or the display panel by shining light onto the face of the plate or panel. In such devices, the light source is disposed outside and in front of the plate or panel face to radiate light onto opaque display indicia disposed on this face which in turn reflects the light to the viewer, thus illuminating the display indicia.
Other prior art devices were developed which were not dependent on reflection of exterior light but instead involved one or more light sources which were disposed inside a housing behind a display face. Such a light source would then shine light through transparent or translucent portions of the display face to illuminate the desired display indicia for the viewer.
This latter form of illuminated display device has taken many forms and involves numerous different features. Two recent examples include Munoz (U.S. Pat. No. 4,475,298) and Monroe (U.S. Pat. No. 5,073,842). Both of these patents generally disclose a box-like light source housing having a forwardly disposed opening in which a partially translucent or otherwise partially non-opaque display panel is mounted. The light source in each housing emits light that passes through the translucent or non-opaque portions of the associated display panel to create an illuminated image.
A principal distinction between Munoz and Monroe (and between other devices similar to each) is that where the Monroe device first transmits light through air within its substantially vacant housing, the Munoz housing is filled with a solid, light-conductive/light-transmitting material upon which is overlaid a partially opaque shield having non-opaque portions formed therein. Light is then directed into an edge of the Munoz light-conductive material which disseminates the light to illuminate the entire display area. The visual image is created by the light which emanates from the display material through the non-opaque portions of the shield. Other examples of illumination devices using similar light-conductive materials are disclosed in the U.S. Patents to Aronoff (U.S. Pat. No. 3,349,511), O'Donnell (U.S. Pat. No. 3,406,475), Redick (U.S. Pat. No. 5,150,960), and Ching Hwei (U.S. Pat. No. 5,177,889). Note that Redick and Ching Hwei describe devices which combine elements of the exterior reflection devices (discussed generally above) with the use of light-conductive materials.
On the other hand, the Monroe device (introduced above), is effective without the use of a solid, light-conductive material. In Monroe, light emits from a light source in the housing and radiates through the air in the housing and then out through the non-opaque portions of the display panel mounted in its forwardly disposed opening. Other U.S. Patents for similar devices include those to Marsala (U.S. Pat. No. 2,045,863), Marks (U.S. Pat. No. 2,108,591) Czarny et al. (U.S. Pat. No. 2,122,027), Rioux (U.S. Pat. No. 2,124,829), Dunnam et al. (U.S. Pat. No. 2,156,753), Ducey (U.S. Pat. No. 2,156,806), White (U.S. Pat. No. 2,171,820), Hoover et al. (U.S. Pat. No. 2,203,785), Aydelotte (U.S. Pat. No. 2,305,372), Vokaty (U.S. Pat. No. 2,305,750), Gladd (U.S. Pat. No. 2,875,539), Murai (U.S. Pat. No. 3,521,391) and Flannery (U.S. Pat. No. 3,921,324).
Even in view of the voluminous prior efforts in this art, there still remains a need for illuminated display devices that have improved features for use and easy installation and which reduce light and water leakage. For example, a problem with the Monroe-like devices is that when one is mounted on the front of a motor vehicle, the seam between the display plate and housing where these components engage is subject to light and water leakage. Light leakage can impair the display image of the device while water can affect its operability and/or substantially reduce its effective life. Note, Monroe does address this problem by teaching the placement of a gasket in this seam particularly to combat water entry. Further, the standard screw attachments of the display plates to the prior art housings are relatively complex in that they require laborious and time-consuming efforts, both during installation and in maintaining, replacing or repairing interior elements such as a light source or a display panel.